1. Field of the Invention
The present invention relates to a piezoelectric vibrator, an oscillator, an electronic part, an electronic apparatus, a method of fabricating a piezoelectric vibrator and a method of fabricating an electronic part.
2. Description of the Related Art
In recent years, there are utilized various electronic parts, for example, a piezoelectric vibrator as a time source, a timing source of a control signal or the like in a portable telephone or a portable information terminal apparatus. There is a piezoelectric vibrator including a hermetically sealed vessel constituted by overlapping a base member and a lid member, and a piezoelectric vibrating piece provided at inside of the hermetically sealed vessel. The inside is hermetically sealed by the hermetically sealed vessel for stabilizing a vibrating characteristic of the piezoelectric vibrating piece by maintaining a periphery of the piezoelectric vibrating piece in a vacuum state. It is well known that the piezoelectric vibrator is provided with a bonding film comprising a metal of aluminum or the like between the base member and the lid member for bonding the base member and the lid member (refer to, for example, Patent Reference 1).
However, when such a bonding film comprising a metal is provided, a plurality of lead-out electrodes for applying a voltage to the piezoelectric vibrating piece cannot be extended on an overlapping face between the lid member and the base member. Because when the bonding film is provided between the lid member and the base member, the bonding film and the plurality of lead-out electrodes interfere with each other and the plurality of lead-out electrodes are shortcircuited.
Hence, it is conceivable to provide a through hole communicating with inside of the hermetically sealed vessel or the like at, for example, the base member and connecting the piezoelectric vibrating piece and an external electrode by way of the through hole.
[Patent Reference 1] JP-A-2000-68780
However, according to the constitution for providing the through hole as described above, a small clearance is liable to be brought about at inside of the through hole by various factors of aging deterioration, impact or the like to pose a problem that outside air invades the inside of the hermetically sealed vessel from the clearance. When the outside air invades the inside of the hermetically sealed vessel, an influence is effected on the vibrating characteristic of the piezoelectric vibrating piece. According thereto, the more the through holes are provided, the more serious is the problem. Further, when the piezoelectric vibrator is further downsized by a request of small-sized formation and high density formation of a portable terminal information apparatus in recent years, provision per se of providing the through hole functioning properly becomes difficult.
Further, when a device of a piezoelectric vibrating piece or the like is of a multiterminals type, a number of the through holes need to be formed at the base member or the lid member, in this case, space is restricted and a reduction in a strength thereof is brought about and therefore, the case cannot meet the request for small-sized formation and high density formation.